Conventional margarine contains about 80% fat. Low-calorie margarine substitute products are well known and on the market which have a much lower fat content, for instance about 40% to 60% by weight fat. One such spread is disclosed in U.S. Pat. No. 3,360,377 to Spitzer et al. The spread of this patent is identified as a low-calorie margarine substitute in the form of a water-in-oil emulsion. In all of the examples of the patent, the fat content is about 39%. The essence of the method of this patent appears to reside in the steps taken to assure that the water-in-oil emulsion is formed and maintained.
Also typical of the prior art is U.S. Pat. No. 4,071,634, to Wilton et al, describing a low-fat spread containing a continuous plastic fatty phase and a dispersed protein aqueous phase, the aqueous phase containing both phosphatides and fatty phase. The total fat content in the examples of this patent appears to be within the range conventionally employed in prior art spreads.
The reason why the art has not gone to lower percentages by weight in fat content is the difficulty experienced in maintaining oil as the continuous phase; that is, preparing a stable emulsion. Both of the above patents are directed to the problem of improving emulsion stability. A fat in a margarine substitute should have a melting point and dilatometric profile close to that of fat in a margarine so that it is quickly melted when used, for instance on corm or toast, and can be consumed without leaving a waxy mouth-feel. However, fats generally used for the preparation of margarine substitutes have melting points and dilatometric profiles more appropriate for achieving emulsion stability than duplicating the properties of fats used in conventional margarine.